This milestone was recorded in the ESO Telescope Bibliography (telbib) on 11 September 2013. Telbib is a database of refereed papers which have been published by the ESO users community, and contains papers dating back to 1996. It is maintained by the ESO Library. All papers use partly or exclusively data from ESO facilities. The database is compiled by scanning the major astronomical journals for scientific papers that contain any of the ESO-defined keywords (e.g., telescope and instrument names). All papers included in the database have been inspected visually to ensure that they directly use ESO observational data.